Monday 18 June 2012 08.00 EDT
First published on Monday 18 June 2012 08.00 EDT

The British military is increasingly relying on unmanned drones to wage war against the Taliban, and has fired more than 280 laser-guided Hellfire missiles and bombs at suspected insurgents, new figures reveal.

In the past year alone, the remotely controlled Reaper aircraft have flown more than 11,000 hours over southern Afghanistan and attacked targets with 105 high-impact precision weapons.

But the use of the drones, which are flown by RAF pilots from a US air force base in Nevada, is raising fresh concerns among human rights lawyers and MPs.

The Ministry of Defence says only four Afghan civilians have been killed in its drone strikes since 2008. However, it also says it has no idea how many insurgents have died, because of the "immense difficulty and risks" of verifying who has been hit.

Instead, the MoD says it relies on Afghans making official complaints at military bases if their friends or relatives have been wrongly killed – a system campaigners say is flawed and unreliable.

"This is nonsense," said Heather Barr, a lawyer for Human Rights Watch, who has been in Afghanistan for five years. "There are many disincentives for people to make reports. Some of these areas are incredibly isolated, and people may have to walk for days to find someone to report a complaint. For some, there will be a certain sense of futility in doing so anyway.

"There is no uniform system for making a complaint and no uniform system for giving compensation. This may not encourage them to walk several days to speak to someone who may not do anything about it."

The UK has been using drones in Afghanistan for the past four and a half years, having bought six Reapers from the US as part of an 'urgent operational requirement'.

The RAF currently uses five Reapers on constant rotation to support Nato's military campaign, and is providing 36 hours of coverage every day. This means two drones are in use much of the time.

Last July, the MoD admitted UK drones had flown a total of 23,400 hours and fired 176 missiles and laser-guided bombs since 2008. By the end of May this year, the totals had risen to 34,750 hours and 281 weapons.

According to the MoD and Nato's International Security and Assistance Force (Isaf), a British drone was responsible for killing four Afghan civilians in a missile strike on 25 March last year. Two insurgents died when two pickup trucks were attacked.

But the MoD says no other civilians have been harmed since then, and Isaf has received no complaints. However, the department also conceded it did not know, and could not estimate, how many insurgents had been killed.

A spokesman said: "For reasons of operational security, we are not prepared to comment on the assessed numbers of insurgents killed or wounded in Reaper strikes.

"As you would expect, following any engagement an assessment will be made of the effectiveness of individual mission strikes. However, because of the limited information available from imagery and immense difficulty and risks that would be involved in collecting robust data on the ground, this information is considered speculative and likely inaccurate."

In December 2010, David Cameron claimed 124 insurgents had been killed in UK drone strikes. But defence officials said they had no idea where the prime minister had got the figure from, and that it had not been provided by the MoD.

Barr said she believed there had been under-reporting of civilian casualties, but it was impossible to know by how much. She said the situation must be addressed, particularly as Afghan security forces were now increasingly taking the lead in military operations, and may also be the first to receive complaints, if they are made.

"The Afghan government does not have a uniform system for looking at complaints into civilian casualties," she said. "The Afghan ministry of defence has its own system; so does the ministry of [the] interior. Both systems are shaky and not very well developed. We keep asking what mechanisms have been set up, but we don't get anywhere. Afghanistan needs a single, understandable, accessible complaints system that reaches out to communities and doesn't rely on self-reporting."

Another human rights lawyer, Erica Gaston, who works for the US Institute of Peace, added: "Nato has come a long way in improving its investigation and reporting but it's far from perfect. Given the difficulty civilians have accessing international military bases, I would doubt any verification system based on citizen reporting alone.

"Depending on the proactivity of Afghan civilians to assess whether a civilian or combatant was targeted would seem to contradict basic international law obligations to take measures to avoid civilian harm."

She added: "Specifically on the drone issue, there has been little to no visibility on how drone targets are selected or reviewed. There have been many cases in Afghanistan and elsewhere in which the visual identification of a "target" through drone technology proved catastrophically wrong. Such past mistakes have raised the bar on the level of transparency and public accountability required. The 'trust us' approach is no longer good enough where drones are involved."

Jim Murphy, the shadow defence secretary, said ministers had to "make every effort to assess the impact of military actions" involving drones.

"They are an important element of modern warfare, and new technologies and their deployment must be constantly refined to minimise civilian casualties. I would expect ministers to always be looking at how the current systems could be improved, working closely with the military."

The Labour MP Madeleine Moon, who is on the Commons defence select committee, said: "Greater priority must be given to ensure those killed in drone attacks are not innocent civilians. Current figures coming out of the Ministry of Defence do not indicate that the level of scrutiny needed is in place. It is imperative that steps are put in place, not only to protect innocent civilians, but demonstrate that have done so."

Chris Cole, founder of the website Drone Wars UK, said it was "Kafkaesque of the MoD to repeatedly claim that only four civilians have been killed in UK drone strikes while at the very same time insisting they do not know how many people have been killed."

The MoD insists it does everything it can to minimise civilian casualties, and on occasions has aborted missions at the last moment, just to be on the safe side. It said it had strict and frequently updated safety procedures "designed to both minimise the risk of casualties occurring and to investigate incidents".